Top burner closure structure



Sept. 30, 1941. c. E. PARKER TOP BURNER CLOSURE STRUCTURE Filed March 30, 1940 4 Sheets-Sheetl N vs, (Toad 0/0410@ 6. M

t- 30, 1941' c. E. PARKER 2,257,397

TOP BURNER CLOSURE STRUCTURE Filed March 50, 1940 4 Sheets-Sheet 2 Ii-mad I G/auae ,6". flax/1e)" ag w M .1 W

oaTTooggys p 1941- c. E. PARKER 2,257,397 TOP BURNER CLOSURE STRUCTURE Filed March 50, 1940 4 Shegfns-Sheet 3 4 SheeFs-Sheet 4 I liik uct Sept. 30, 1941. c E PARKER TOP BURNER CLOSURE STRUCTURE F led Ma ch 30 1940 mm Cyauo/e E Dow/Ken A; M M

metallic support.

Patented Sept. 30, 1941 UNITED STATE TOP BURNER Claude E. Parker, Chicago, 111., asaignor to Gas Products Corporation, Chicago, 111., a corporation of Illinois Application March 30, 1940, Serial N0. 326,883

Claims.

The present invention relates to improvements in closure or hearth structures adapted to be removably supported in a gas stove or range cooking tops in the burner openings of the top panel.

Theinstant application is a continuation in part of my copending application Serial No. 272,984, flied May 11, 1939. In said copending application I have described and claimed a novel form of cooking top structure in which a burner head, registering with a hole in the top panel of the stove, has above it an overlying hearth or closure structure apertured for the passage of flames from the burner head to a utensil; and which closure structure coacts with the head to define a novel system of secondary air supply passages to the flames. I have referred tothe structure noted as a "closure structure" sinceit either alone or in conjunction with the burner head givesthe stove top a generally closed appearancealthough, as noted, it does have openinss in it for issuance of flames so as to achieve the high degree of efliciency peculiar to an open top style of stove in whichthe flames play directly on the utensil beingheated. The particular :closurestructure shown, byway of exemplie flcation, in said copending application is made in part of refractory material in order better to withstand the intense heat of the blanket of flames confined between it and the closely overlying utensil bottom as well as for other reasons incident to efllcient and efiectiveoperation. This same closure structure, as well as certain modifled forms thereof, have been illustrated herein. The present invention has primarily to do with improvements in the closure structure per se or, in other words, with a subcombination of the general cooking top structure disclosed in said copending application and in its broadest aspects embraces the use of closure structures made in one piece as well as those embodying a refractory or other separate element; or elements on a Generally stated, it is an object of the invention to provide, a novel closure structure of the character indicated which is of unitary form such that the whole structure and its associa ed utensil seating arrangement can be removed from the stove and handled as a unit.

Another object of the invention is to provide such a closure structure having a novel contour or shape such as efllciently to apply heat to an overlying utensil bottomand which will, however, impart to the stove top a finished and attractive appearance. I

Another object is to provide a structure of the type set forth of such characterthat efiectual application of the heat of combustion to a utensil is accomplished while preventing direct flame impingement on the utensil supports, so as to protect the finish of the latter.

In its more specific aspects, it is an object of the present invention to provide a closure or hearth structure of the type indicated embodying one or more of the following features: (a) A novel interlocking arrangement between a plurality of refractory elements anda metal cradle or carrier for them such that the parts are normally'held together as a unit for removal oi. the entire closure structure from the stove for cleaning, etc., but in such manner that the refractory elements can be readily detached, if desired, for purposes of replacement and the like; (b) a cradle having abrasion-resistant metal utensil supports on it adapted to perform the further function of holding in place a set of removable refractories; (c), a strong metal cradle arranged to protect a set. of refractories on it from mechanical shock, as well as to support the same; and (d) a novel interlocking arrangement between the cradle and refractories for holding the latter in place without danger of breakage of the refractories due to inequalities in the coefficients of thermal expansion of the materials comprising the cradle and refractories, respectively.

Further objects and advantages of the invention will become apparent as the followingdescription proceeds, taken in connection with the accompanying drawings in which:

' Figure 1 is a plan view of a closure structure embodying the invention.

Fig. 2 is a transverse sectional View taken substantially along the line 2-2 in Fig. 1.

Fig. 3 is an exploded perspective view of the closure structure of Fig. 1.

Fig. 4 is an exploded perspective view oi." a modifled form of closure structureembodying the invention.

Fig. 4 is a transverse sectional view, on reduced scale, or the closure structure 01' Fig. 4.

Fig. 5 is a plan view of a further modified form of closure structure embodying the invention.

Fig. 6 is asectional view taken substantially along the line 5-6 in Fig. 5.

Fig. 7 is a fragmentary side elevation of the structure of Fig. 5, showing the end of one of the utensil supports.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe indetail, the preferred embodiment, but

For purposes of exempliflcation the invention has first been shown (Fig. l) and described herein as embodied in a closure or hearth structure comprising a generally disk shaped assembly adapted to be seated as a unit in a burner hole in the top panel over a gas burner head (not shown). The function of such a closure structure is, from an appearance standpoint, to conceal the underlying burner head and substantially to fill the aperture in the top plate so as to form a generally coplanar continuation of the top plate instead of leaving a more or less open and unsightly hole in it. From a thermal efllciency standpoint, the closure structure serves to confine beneath a closely spaced overlying utensil bottom a blanket of intensely hot flames,

-to reflect heat to the utensil bottom, and to store up heat which is subsequently radiated to the utensil bottom.

As a principal element the first illustrative closure structure includes (see Fig. 3) a metal cradle or carrier III, with which are removably interlocked a plurality of structurally separate refractory elements H and I2, and having rigid with it a series of metal utensil supports l3. Also included in the assembly are three auxiliary metal supporting fingers H, which cooperate with the cradle to hold the refractory elements in place on the latter as hereinafter set forth.

The cradle I is desirably made of cast iron and includes a circular border ring I 5 with an upstanding annular flange IS on it. The utensil supports l3 are, in the present instance, integral with the cradle and extend along three equidistant radii. It will be observed that the rounded outer ends or noses ll of the utensil supports project laterally beyond the periphery of the eradle so as to form buffers. When, for example, a heavy cast iron skillet or pot is slid across the top of the stove onto the hearth it rides up on the adjacent utensil support nose and onto the top surfaces of the utensil supporting arms, thereby protecting the more fragile refractories from mechanical shock. On the cradle Ill intermediate the utensil supports are three inwardly projecting integral webs l8 on which the refractory elements l2 are seated (see also Fig. 2).

The refractory elements H, l2 are arranged to present generally coplanar top surfaces forming a heat reflecting and confining hearth of shallow bowl shape in closely spaced relation beneath a utensil (not shown) seated on the supports I3. The refractory elements may be made of any suitable heat resistant material. Desirably they are made of ceramic material having a glazed vitric coating'fused on it at a temperatureof about 2500" F., or in other words, well above any temperature encountered in use even with flames from the gas burner lapping directly on it, a suitable material for the purpose being sold under the the trade name Parkerite."

In the instant construction the refractory elements II are here shown (Fig. 3) as three in number and are fashioned in the form of elongated fingers lying along equidistant radii from the center of the assembly (see also .Fig. 1). These elements II are notched at their outer ends as indicated at I! in order to embrace and interlock with the upright base portions 2| of the respective utensil supports I3. Each of the ceramic elements H underlies a respective one of the utensil supporting arms 13 throughout substantially the entire length of the latter, thereby thermally insulating it from an underlying burner. The burner head itself (not shown) may, if desired, be made in a three-arm form described and claimed in my copending application Serial No. 324,470, filed March 18, 1940, and arranged with one burner arm underlying each of the elements H. To hold'the refractory elements II in position the auxiliary metal fingers ll are disposed in supporting relation beneath respective ones of them. The cradle III is notched as indicated at 2| (Fig. 3) to receive the outer ends of the metal supports l4 and the latter are fixed in place on the cradle by screws 22 (Fig. 2).

Intermediate the finger shaped elements H are located the other three refractory elements I! (Fig. 1). These elements l2 are generally sector shaped and present arcuate inner edges. The inner ends of the finger shaped elements II are enlarged in a lateral direction (Fig. 1) so as to present complemental arcuate edges spaced from the inner edges of the elements II and cooperating therewith to define elongated arcuate slots 23 of substantially uniform width from end to end, in the closure structure through which flames from an underlying burner head may issue. It will be observed that the intermediate elements are shallowly dished downward and inward so as to receive above them flames pro- Jected laterally outward through the slots 23. On the surfaces of the elements l2 are radially extending ribs 25 which direct the flames toward the periphery of the unit and which incandesce in the intense heat to which they are subjected to radiate heat to an overlying utensil. Similarly, the elements II are provided with incandescable ribs 21 along their marginal edges which border the flame slots 23.

Further flame apertures in the hearth are formed between the inner edges of the refractory fingers H, which are opposed to each other (Fig. 1). It will be seen that they are spaced apart to define an open center 28 connected through slots 29 with the main slots 23, and beneath which openings 28, 29 may be located a suitable center simmer burner or the like (not shown).

By shaping the elements ll, l2 as set forth, particularly 'withthe dished intermediate elements l2 leading out from the flame slots 23 and separated by higher finger elements It on which the utensil seats l3 are located, the flames issuing through the slots 23 are effectually distributed over the bottom of a utensil resting on the seats l3. Since these slots 23 are, however, curved at their cuter ends to follow along the sides of utensil supporting elements, the flames issuing through the slots are directed generally away from th utensil supports and never impinge on them so that their finish is not impaired. Not only is the heat confined in a blanket of high temperature beneath the utensil but the glossy vitric surfaces of the refractory elements intercept its downward flow and reflect it efiectually to the utensil bottom. Heat whlgi is gradually stored in the hearth is subsequently radiated to the utensil even after the burner is turned ofi so that cooking can be continued at such time and maximum emciency achieved. In other words, a so-called fast start in cooking is achieved because the hearth absorbs heat but very slowly, most of it being directed initially the same, in view of their construction heretofore set forth.

Of. particular importance in the present instance is the arrangement for holding the various ceramic elements ll, l2 in assembled relation on the cradle Ill so that the entire closure structure may be handled as a unit without I danger of inadvertent dislodgment of any of the. elements. Though the refractory parts ll, l2 are structurally separate, as heretofore described, i'or the sake of simplicity in their original manufacture and so that they can,'if necessary, be removed or replaced, the whole assembly is normally unitary. As a result the closure structure can be readily lifted from the stove top as. a unit, either for washing and cleaning of the cover itself, or for cleaning or adjustment of interiorly located parts in the stove such as the burner head.

To hold the intermediate refractory elements l2, in place on the cradle I ll these elements are interlocked at their ends with the elements II. For this purpose integral shoulders or' ribs 24 (Fig. 3) are fashioned on the ends of each of the elements l2 while complemental ribs or shoulders 25 are fashioned at the sides of the outer end portions of the elements H. When the parts are disposed in assembled relation the elements. I2 rest on the cradle webs l8 and are held against displacement upwardly by the overlying interlocking projections or ribs 25 on the elements ll. These elements II are in turn interlocked with the cradle by the utensil supports I3. Thus the engagement of the notched ends of the elements II with the supports prevents their displacement laterally in the plane,

of the cradle while the overlying arms l3 prevent the flngers II from being displaced upwardly. Finally, the underlying auxiliary fingers I! hold the fingers ll against downward displacement. The peripheral flange IS on the cradle holds the elements l2 against movement radially outward of the cradle. In this connec- P tlon it should be noted in Fig. 2 that the elements 12 are peripherally grooved so as to receive the flange I6 and are thus seated snugly inthe more or less cup shaped cradle.

It will thus be seen that all of the elements s of the closure structure are. thoroughly interlocked with each other so that the structure can be handled as-a unit and turned in anydirection without possibility of having one of the structurally separate elements fall off. On the other hand, the use of interfltting or interlocking joints between all of the parts of dissimilar material makes possible the use of sufficiently wide clearances between their abutting parts as to permit of inherently different expansions when heated without danger of cracking the refractories. In this connection it should be noted that the. only screws used are the screws 22 which connect only metal parts, viz., the cradle l and metal fingers I, as distinguished from connecting a refractory part and a metal part.

In assembling the closure structure of Figs. 1 to 3 the intermediate refractory elements l2 are seated on the cradle webs it. The finger shaped refractory elements H are then pushed into place, beneath the utensil supports "in a direction longitudinally outward of the latter. The ribs 24, 25 are thus brought intointerlocking relation so that the elements H hold the intermediate elements 12 in place. Then, to complete the assembly the metal fingers ll are screwed in place beneath the refractory fingers II. By these simple manipulations the entire structure is assembled as a firmly interlocked unit.

In Fig. 4 I have shown a modified form of hearth or closure structure also embodying the invention. It differs from that of Figs. 1 to 3, described above, primarily in that instead of using refractory fingers like the elements ll, overlaid by separate metal utensil supporting fingers, these two elements have been combined in the form of metal fingers i3. These elements it, together with a single set of intermediate refractory elements II! are removably supported on a cradle l0.

In this instance the cradle I II is much like the cradle Ill described above, being made of cast iron or the like and including a circular border ring l5 with an upstanding annular flange It on it. Projecting inwardly from the border ring iii are webs l8, which carry the refractory elements l2. In this construction the utensil supports are removably, though rigidly, attached to the cradle. For this purpose bosses, 20* are formed on the cradle ID at three equally spaced points intermediate the webs l8. Suitable screws (Fig. 4*) are inserted through holes 22' (Fig. 4) in these bosses and are threaded in the butt portions ofthe utensil supporting fingers I3 to hold the same in position.

The intermediate refractory elements l2 are of substantially the same form and construction a the elements (2 of Figs. 1 to 3, and are desirably made of the same glazed ceramic material heretofore described. In this instance,

however, they have been shown as being of somewhat smoother or less, irregular contour having but two ribs 26 on each of them.

The utensil seating or supporting elements l3 may be made of cast metal or the like and plated, enameled or polished to give them a decorative and pleasing finish. Adjacent their outer end portions are provided laterally projecting ribs or wings 25 which overlie and interlock with ribs 24 on the ends of the intermediate elements I2 so asto hold the same in position on the cradle I0 in the same general manner as heretofore described for the interlocking parts in the device of Figs. 1 to 3.

To form three generally arcuate flame slots arranged in triangular configuration, like the slots 23 of Fig. 1, the inner edges of the intermediate refractory elements l2 are again made generally arcuate in form. In the present instance, however, the inner ends of the metal fingers l3" are splayed or enlarged laterally to match the curvature of the inrr'r edges of these elements Ii." just as were the ends of the refractory fingers I I in Fig. 1.

In assembling the closure structure of Fig. 4

the refractory elements l2 are seated on the webs l8 of the cradle. are then seated on the A second modified form of closure structure embodying the invention has been shown in Figs. 5 to 7. In this particular instance no ceramic material is used but, instead, the whole unit is made in the form of a single integral casting ormolding. It will be observed, however, that its top surface is of substantially the same contour as that for the cover structures heretofore described. Since no refractories are used it is unnecessary to provide a separate cradle element. In the present instance the closure structure embodies three radially extending finger portions l3 of substantially the same surface contour as the fingers l3 described above. The top surfaces of these fingers are in the form of longitudinal ridges on which a utensil may be seated, the outer end portions of the ridges being elevated above the rim of the bowl (Fig. '1). If

desired, in order to simplify the provision of a contrasting finish on the finger portions I3 and the remainder of the bowl, the fingers can be made as separate metal castings screwed to the bowl like the fingers l3 described above. Intermediate these fingers portions l3 and integral therewith are intermediate portions l2 of shallow dish or bowl shape and corresponding generally to the contour of the intermediate elements l2 and l2 heretofore described although they are preferably dished somewhat more deeply inasmuch as they are made of metal and, hence, cannot well withstand direct fiame impingement without burning off their finish. On these intermediate portions |2 are raised bosses 26, set well back from the center of the structure so as to be out of its hottest portion and forming auxiliary or intermediate utensil supports.

It will be observed in Fig. 5 that the inner edges of the intermediate portions [2 of the structure are convexly curved while the inner ends of the utensil supporting fingers l3 are splayed outwardly in complemental form to define fiame emission openings 23' through which fiames from an underlying burner head may issue.

The cover structure of Figs. 5 to '7 is desirably made of cast iron and has a porcelain enamel finish. Since it is fashioned as a single unit it can be readily handled during removal for washing, etc. It, like the other closure structures heretofore described, substantially closes the burner aperture in the stove top plate, from an appearance standpoint, so as to give it an appearance of smooth, over-all glossy finish and yet is apertured for the issuance of flames from an underlying burner head so that they can play directly on a utensil seated on the fingers I3 Since these utensil supporting fingers are desirably formed integrally with the mass of metal which constitutes the remainder of the closure structure or at least fixed rigidly to it, heat imparted to them from the flames is distributed throughout the closure structure, thereby insuring a sufficiently low over-all temperature for the structure, that liability of burning off of its finish is obviated.

In each of the several illustrated embodiments of my invention the three spaced radial portions of the cover structure coact to form a central section adapted to overly and substantially conceal. an underlying burner, while the three intervening portions cooperate in the formation of an outer section having downwardly offset surfaces over which the hot gases from the burner may discharge through outlet means consisting of slots 23 or 23'. While the several cover structures illustrated are in a form adapted for use with a burner of triangular shape such as that disclosed in my copending application Serial No. 272,984, it is understood that cover structures for use with burners of other shapes may be provided by those skilled in the art without departing from the spirit and scope of my invention as defined by the appended claims.

I claim as my invention:

1. A closure unit of the type set forth comprising, in combination, a plurality of radially extending portions presenting utensil seating surfaces of elongated ridge form on their tops, means intermediate said radial portions presenting wide top surfaces dished shallowly downward and inward, the inner edges of said surfaces being convexly curved and the inner ends of said radial portions being splayed laterally outward to match generally the curvature of said edges but spaced therefrom to define therewith elongated slots for the issuance of flames through said slots and over said top surfaces.

2. A closure unit of the type set forth comprising a generally shallow dish shaped unitary structure having rigid with it elongated utensil supports extending radially inward toward its center and presenting utensil seating surfaces spaced above the perimeter of the dish, and said dish having a plurality of slots therein intermediate said supports with the ends of the slots curved outwardly toward the edge of the dish and lying along the adjacent sides of the supports for the emergence of flames through such slots and over-the portions of the dish intermeprising a generally ring shaped metallic cradle open in its central portion, a plurality of elongated finger elements projecting radially inward from the periphery of said cradle toward its center, means removably fixing said finger elements to the cradle, said finger elements having utensil seating means 'on their tops, intermediate refractory elements seated on the cradle between adjacent ones of said finger elements, and said finger elements having lateral projections on their outer end portions overlying complementally formed portions of the ends of the intermediate elements in interlocking relation therewith to hold the same on the cradle.

4. A closure unit of the type set forth, comprising a generally ring shaped metallic cradle open in its central portion, a plurality of elongated finger elements projecting radially inward from the periphery of said" cradle toward its center, means removably fixing said finger elements to the cradle, said elements having utensil seating means on their tops, intermediate refractory elements seated on the cradle between adjacent ones of said finger elements, said intermediate elements being shallowly dished downward and inward toward the center of the unit and having convex inner edges, the inner ends of said finger elements being enlarged laterally to conform generally to the curvature of said convex edges but disposed in spaced relation thereto to define therewith slots for the emergence of flames over said dished intermediate elements, and said finger elements having lateral projections on their outer end portions overlying complementally shaped portions of the ends of the intermediate elements in interlocking relation therewith to hold the same on the cradle.

5. A closure unit of the typeset forth, comrefractory hearth elements removably seated on said cradle, and means including a plurality of metal utensil supporting fingers rigid with said cradle and above the refractories and interlocked with the latter for holding the same in position on said cradle.

6. In a closure unit of the type set forth, the combination of a generally ring shaped metal cradle, metallic utensil-seating fingers fixed on said cradle and projecting radially inward to ward its center from spaced points about its periphery, a plurality of refractory finger elements disposed beneath respective ones of said utensil-seating fingers, means for releasably clamping said refractory fingers against the undersides of the utensil-seating fingers, intermediate refractory elements seated on the eradle in the spaces intervening between successive ones of the refractory'fingers, and the outer end portions of said refractory fingers having integral lateral projections thereon overlying commediate elements in interlocking relation therewith to hold the intermediate elements against dislodgment from the cradle. 7

7. In a closure unit of the type set forth, the

combination of a generally ring shaped metal .plementally shaped end portions of said interments disposed beneath respective ones of said downward and inward toward the centervof the unit, the inner edges of said intermediate elements being convexly curved, the inner end por-. tions of said refractory fingers being enlarged laterally and spaced from said inner edges of said intermediate elements to define therewith slots for the passage of flames through such slots and oversaid dished intermediate elements, and the outer end portions of said refractory fingers having integral lateral projections thereon overlying complementary shaped portions of said intermediate elements in interlocking relation therewith to hold the intermediate elements against dislodgment from the cradle.

8. In a closure unit of the type set forth, the combination of a metal cradle including a border ring, a plurality of metal utensil-seating fingers projecting radially inward toward the center of the ring from circumferentially spaced points on it and joined to the ring at their outer ends by upstanding posts, refractory finger elements underlying respective ones of the metal fingers and notched at their outer ends to embrace said posts in interlocking relation therewith, intermediate refractory elements seated on said cradle in the spaces intervening betweensuccessive ones of the refractory fingers, and means including interlocking projections on the adjacent portions of said refractory fingers and intermediate elements for releasably holding the latter in position on the cradle.

9. In a closure unit of the type set forth, the combination of a metal cradle including a border ring, a plurality of metal utensil-seating fingers projecting radially inward toward the center of the ring from circumferentially spaced to the inner edges points on it, means for releasably fixing the outer endportionsofsaidfingerstosaidring,intermediate refractory elements seated on said cradle in the spaces intervening between succesive onesofsaidfingemandmeansincludinglateral projections on the outer end portions of said fingers overlying complementaliy shaped end portions of said intermediate elements in interlocking relation therewith to hold the intermediate elements against dislodgment from the cradle.

10. 1n a closure unit of the type set forth, the combination of a metallic cradle including a border ring. a plurality ofmetal utensil-seating fingers projecting radially inward toward the center of the ring from circumferentially spaced points on it. means for releasably fixing the outer end portions of said fingers to said ring, intermediate refractory elements seated on said cradle in the spaces intervening between successive ones of said fingers, said intermediate elements being shallowly dished downward and inward toward the center of the cradle and the inner edges of said intermediate elements being convexly curved, means including interlocking projections on the adjacent portions of the 'saidfingers and intermediate elements for releasably holding the latter in position on the cradle, and the inner end portions of said metal fingers being enlarged laterally to provide edges generally complemental of said intermediate elements and spaced therefrom, thereby to define slots for the emergence of flames through such slots and over the dished intermediate elements.

11. A closure unit of the type set forth comprising a single integral molded dish of shallow contour, said dish having a plurality of radial ridges raised thereon to form utensil seats, the longitudinal top surface of said ridges being elevated at their outer end portions above the rim of the dish, said dish having a plurality of slots in its central portion disposed respectively between successive ones of saidridges, the ends of "said slots being curved outwardly toward the perimeter of the dish and lying along the sides of said ridges, the outer edges of said slots being depressed for the emergence of fiames through said slots and over the portions of the dish intervening between said utensil-supporting ridges.

12. In a closure unit of the type set forth comprising, in combination, a plurality of radially extending portions presenting utensil seating surfaces of elongated ridge form: on their tops,

, means intermediate said radial portions presenting wide top surfaces dished shallowly downward and inward, the inner edges of said surfaces being convexly curved and the inner ends of said 7 portions being splayed laterally outward to match I generally the curvature of said edges but spaced therefrom to define therewith elongated slots for the issuance of flames through said slots and over said top surfaces, and the inner ends of said radially extending portions coacting to define a central opening in the closure unit for the issuance of flames centrally of the unit.

13. A closure uni-t adapted to be removably seated in the burner opening of a stove top panel or the like and comprising an integral metallic disk having a border portion presenting a topsurface of substantial lateral width and sloping downwardly from its perimeter inwardly toward the center, a plurality of circumferentially spaced radial portions rigid with said border portion and extending longitudinally inward from points located above the perimeter of said border portion toward the center of the unit, and utensil emission slots.

14. A cover for a gaseous fuel burner comprising, in combination, a circular disk having circumierentially spaced radially extending portions presenting utensil seating surfaces and other portions intervening between said radial portions and presenting wide top surfaces disposed on a plane below said radial portions, said disk having apertures therein opening outwardly along the sides of said radial portions and adapted to permit of the discharge over said intervening portions of the gases of combustion.

15. A. burner cover unit for a gaseous fuel cook stove, comprising a central section providing utensil seating surfaces, and an outer section presenting wide top surfaces offset downwardly from the top of the central section and extending outwardly therefrom, and outlet means at the side edges of said central section and above the inner edges of the outer section for the escape of products of combustion outwardly above said outer section.

- CLAUDE E. PARKER 

